Three design strategies directly related to the development of instructional materials for rule learning were investigated. In the first of two experiments using both male and female tenth grade students, the degree of divergence between instances showed that contrasting irrelevant features resulted in better performance than matching irrelevant features. The data analysis from experiment 2 showed that when two contextually similar rules were learned simultaneously, student performance was superior to that of students who learned the rules successively. When the students were provided with an analysis of how a given instance represented the application of a grammatical rule, performance was better than without this analysis. The results were discussed in relationship to a prescriptive theory of instruction. (Author/LL)